Shaped-charge well perforator



United States Patent O SHAPED-CHARGE WELL PERFORATOR Louis Frank Jilly, Inglewood, Calif., assignor, by mesne assignments, to Borg-Wamer Corporation, Vernon, Calif., a corporation of Illinois Filed Oct. 9, 1952, Ser. No. 313,895

1 Claim. (Cl. 102-20) This invention relates to perforators for well bores and casings therein for the purpose of making openings in the formations adjacent the well bore or for perforating the casing in order that fluid from the formations may enter the casing.

Multiple-shot gun perforators are now extensively employed in the oil industry and are generally either of the bullet type or the shaped-charge type. The bullet type guns usually comprise an elongated barrel or body in which a plurality of bullet barrel units are secured, the tiring of the bullets being usually accomplished by either a suitable fuse system or an electrical conductor system extending the length of the gun body. Multipleshot shaped-charge perforators heretofore have generally followed a construction similar to the bullet type construction, wherein a fluid-tight, metallic shell is provided and formed with a plurality of laterally directed, longitudinally spaced-apart openings which permit the placing of the shaped charges therein in alignment with the openings. A suitable fuse or electrical conductor system may be provided for tiring the shaped charges which is similar to the bullet type tiring method mentioned above. These multiple-shot shaped-charge perforators of the before-mentioned types are subject to^or have inherent disadvantages, particularly the expensive construction involved and the diliiculty of preserving adequate liuid seals for the fuse or conductor systems and for the openings or ports through which the perforating charges re. These diiculties and disadvantages are augmented by the extremely high uid pressures and temperatures which obtain in many of the deep wells now being drilled. These high pressures and temperatures tend to cause breakdown of the protective coatings of the fuses and conductor insulations and leakage of the gun bodies, which at times cause partial or complete failure of the guns.

The present invention has been developed to overcome these disadvantages by providing a simple pressureand temperature-resistant assembly of shaped-charge units, a major portion of the structure of which consists of relatively small diameter tubing which contains the ring fuses for the shaped charges, and which tubing can be constructed to stand the high pressures encountered, and yet is etfective for the tiring of the shaped charges.

It is therefore an object of the invention to provide a multiple-unit shaped-charge perforator which does not require a conventional body of substantial construction.

Another object of the invention is to provide a multipleshot shaped-charge perforator wherein a plurality of shaped-charge units are assembled together in a light, open framework.

An additional object of the invention is to provide a perforator as in the previous object, wherein the framework for supporting the shaped charges is constituted essentially of the fuse system for firing the shaped charges.

A further object of the invention is to provide a novel shaped-charge perforating device which is itself substan- 2,947,251 vPatented Aug. 2, 1960 ICC 2 tially disintegrated upon the tiring of the units and a minimum of objectionable debris is left in the casing or well bore.

The objects of the invention are accomplished, in brief, by providing a multiple-unit shaped-charge perforator comprising an elongated, open framework of relatively small, light, expendable metallic tubes disposed in spaced relation about a common axis, in which framework the shaped charge units are positioned and secured, and wherein one or more of the tubes contain a fuse or electrical conductor for firing a plurality of the shapedcharge units so assembled.

Other objects and advantages will vappear and be brought out more fully in the following specification. reference being had to the accompanying drawing forming a part thereof and in which like reference characters refer to like parts. In the drawing:

Figure 1 is an elevational view of the general assembly of the perforator embodying the present invention;

Figure 2 is a fragmentary detail view, partly in longitudinal section, of a portion of the apparatus of Figure l; and

Figure 3 is an enlarged cross-sectional view taken on line 3 3 of Figure 1.

Referring to the drawing more in detail, the numeral 10 indicates a somewhat elongated head member having an upper cap housing portion 10a and a coaxial lower detonator housing portion 18. The cap housing portion is provided with an axial bore 11, which is of reduced internal diameter at the lower end, as shown at 11a, and at the upper end is of larger internal diameter and is provided with internal threads 12 for screwed connection with the threaded lower end portion 13 of an adapter tube 14. The adapter tube 14 is provided with suitable means, such as set screws 14a, for attachment to a suspension conductor cable 15. The cap housing 10a of the head member 10 has a reduced, externally threaded lower end 16 for connection to the threaded bore portion 17 of the upper end of the detonator vhousing 18. 'I'he detonator housing 18 has a somewhat enlarged or flared lower end 19 formed with three bores as shown at 20, the inner ends of which bores open into a main booster charge chamber 21 which is in communication at its upper end with the before-mentioned bore 11a of the upper cap housing 10a. The head member 10, including the cap housing 10a and the detonator housing 18, and also the adapter tube 14 are preferably made of light, frangible material, such as aluminum or brass. Bores 20 are directed divergingly downwardly at equal angles with respect to the longitudinal axis of the detonator housing 18faud the head member 10, and the outer or lower end of each bore 20 is provided with threads 22 for engaging the upper threaded end portion 23 of a tubular fitting 24, each of which, in turn, receives the upper end of a tiring tube 25. Each tube 25 is formed of a suitable light metal, such as aluminum, and one or more of these tubes may contain a suitable fuse 26, such, for; example, that known commercially as R.D.X. Primacord. Tubes 25, preferably but not necessarily three in number, are disposed in substantially parallel, laterally spaced-apart relation about the extended longitudinal axis of head member 10. Except for the upper ends, which are curved inwardly toward aeeaasi end thereof in which is slidably received a side portion of one of the tubes 25. A pair of similar notches or grooves 29 are provided at opposite sides of the forward end of the units to receive the other two tubes 25. A plurality of triangular strap members 30 surround the tubes 25 at points intermediate the shaped-charge units and serve to form a substantially rigid assembly composed primarily of the tubes 25 and the shaped-charge units 27.

A main booster charge of explosive 31 is suitably arranged and provided in chamber 21 of detonator housing 18, and an auxiliary booster charge of explosive 32 is placed in each bore 20 for igniting the end of the adjacent Primacord fuse 26 carried by the associated tube 25. This auxiliary booster charge 32 is preferably Eli-Grade Cyclonite explosive, manufactured by E. I. du Pont de Nemours & Co., conta-ined in an aluminum or copper shell which is crimped to the upper end of the Primacord fuse 26. An electric blasting cap 33 is positioned in bore 11a of cap housing 10a adjacent the booster charge 31 and is provided with conductors 34 and 35 which extend upwardly through holes in a plurality of discs 36 and resilient washers 37 in bore 11 into adapter tube 14, washers 37 being compressed by the dises 36 to provide a duid seal around conductors 34 and 35. The cap housing member 10a is formed with an annular groove 38 adjacent the inner ends of threads 16, in which groove is positioned a fluid seal ring 39. Conductor cable 15 carries therein an insulated conductor 40, the lower end of which is extended downwardly from the end of the cable in adapter tube 14, and thence may be brought out through a slot 41 therein for suitable connection to conductor 34 of the blasting cap 33, the insulated, covered joint on the end of the insulated conductor being indicated at 42. The return or ground conductor 35 of the blasting cap 33 may be secu-red to a screw 43 or otherwise suitably electrically grounded to the adapter tube 14 or to the steel sheath of the conductor cable 15. Each tube fitting 24 is formed with a bore 44 into which the end of one of the fuses 26 extends, the bore being enlarged at 45 to receive the upper end of the associated tube 25, and a further enlargement 46 of the bore 44 is adapted to receive a portion of a packing or sealing ring 47 which is compressed by a packing nut 48 threaded-ly connected at 49 to fitting 24. The lower ends of tubes 25 are curved inwardly, as shown in Figure l, and closed and sealed in any suitable manner, such as by plugs or screws 25a.

As best seen in Figure 3, each of the before-mentioned shaped-charge units 27 comprises a fluid-tight housing having a rearward hollow body portion 50 and a forward cover portion 51, constituted preferably of porcelain or similar ceramic or like material, and preferably glazed to prevent liquid absorption. The cover 51 is secured to the body portion 50, after assembly of the shaped ch-arge therein, and sealed together at 52 by suitable sealing material, such as, for example, #801 sealer made by Minnesota Mining & Manufacturing Co. The shaped charges contained within the housings 50, 51 are comprised of an open-ended metallic, cylindrical shell 53 containing a body of high explosive material 55 formed with a forwardly directed, conical cavity lined with a conical metallic liner 56, preferably made of copper or similar material, as is well known in the shaped-charge art. The shaped charge is secured within the cavity of the body portion 50 of the housing by means of a locking or wedging ring 54. A priming or detonating charge 57 is suitably centrally positioned in the rear end of shell 53, opposite the external notch 28 in body portion 50 of the housing, and adjacent one of the tubes 25 containing the Primacord fuse 26. A protective metal cap may, if desired, be secured on the forward end of cover '1 of the charge unit 27, as shown at 58.

Shaped-charge units 27, any number of which may be used, are grouped in any manner and order of firing as may be desired, and are preferably arranged facing in dierent directions. 'Ehe particular details of construction of the shapedcharge units 27, apart from the combination here disclosed, are not essential parts of the present invention, which is directed to the general construction and assembly of the perforator, and the shapedcharge units are described more fully in the copending application of Will H. Lindsay, Ir., Serial No. 326,291, tiled December 16, 1952.

In the assembly .of the gun perforator as shown in Figure 1, the shaped-charge units 27 are placed in posi- -tion between the tubes 25 as shown, and the bands 30 adjusted in position along tubes 25 starting from the lower end. The dimensions of the bands 30 are such as to dedect the tubes 25'inwardly toward one another a slight Iamount so as to securely grip and hold the shaped-charge units in spaced arrangement between the tubes. After the gun perforator has been assembled as shown, it may be connected to the cable 15, and to facilitate the splicing operation the ungrounded conductor extending therefrom may be brought out through slot 41 and connected to the ungrounded conductor 34 of the gun perforator. The conductor 35 may also be brought out through the slot A41 and grounded to the adapter tube at 43. The perforaltor is then in condition for operation and may be lowered into a well bore, either open-hole or cased, fluid-filled or empty, and after being brought to the desired level may be fired by application of a source of electric current between the cable conductor 40 and the cable sheath, the electrical return circuit thus being provided by the sheath of the cable or the ground. The thus applied electrical current will lire blasting cap 33, which res the main booster charge 31 in chamber 21 and the auxiliary Ibooster charges 32, thus detonating the fuses 26, and these fuses substantially simultaneously re the several detonators 57 of the respective shaped charges 55. Upon the firing of the shaped charges, as before described, the shaped-charge housings 50, 51, tubes 25, bands 30, cap housing 10a, and detonator housing 18 of head member 10 are substantially disintegrated, leaving the lower end of the conductor cable free to be retrieved from the borehole, and leaving substantially no debris of objectionable size in the Well or casing which would otherwise require removal by a bothersome bailing operation or remain in the well, hampen'ng further operations or production.

It will be understood that the foregoing description is illustrative rather than restrict-ive of the invention, and that changes and modifications may be made without departing from the spirit and scope of the subjoined claim.

What is claimed is:

A destructible perforating apparatus for use in borcholes comprising a vertically' elongated head member; means for attaching a ca'ble to said head member at the upper end thereof, said head member providing a sealed chamber therein; detonator means in said chamber; three thin-walled exible Itubes disposed in substantially parallel, spaced-apart relation about the extended vertical axis of said head member and arranged to form a triangular shaped framework of substantially uniform lateral dimensions throughout a major portion of the length thereof, the ends of said tubes at the upper end of said framework being curved inwardly toward each other and being sealingly and rigidly attached to the lower end of said head member with the bores of the tubes in communication with the chamber in said head member, and the ends of said tubes at the bottom end of said framework being curved inwardly; means sealingly closing the bores of said tubes at the bottom end of said framework; a plurality of shaped-charge units having fluid-tight frangible housings vertically spaced apart along said framework, the housing of each unit providing three transverse grooves, each groove slidably receiving a side portion of one of the tubes of said framework, each of said units containing a lined shaped-charge and a priming charge therefor positioned opposite one of said grooves and adapted to be detonated by a fuse in the bore of the tube that is received in said one of said grooves; a plurality of endless bands of triangular shape encircling said three tubes and being Itensioned thereabout, one of said bands being positioned below the lowermost of said units and the others of said bands being positioned one substantially midway between each pair of adjacent units, the dimensions of said bands being such as to deect said tubes inwardly toward one another between adjacent units to securely grip and hold said shaped-charge units in compression between said tubes; said bands and said shaped-charge units being vertically spaced from one another and being supported solely by said tubes, where by to form a substantially rigid assembly projecting from said head member and being composed essentially of said tubes, said shaped-charge units, and said bands; lengths of fuse running through the bores of said tubes and arranged to be detonated simultaneously by said detonator means and to detonate said priming charges; and means for initiating said detonator means.

References Cited in the iile of this patent UNITED STATES PATENTS 2,414,349 Alexander Ian. 14, 1947v 2,616,370 Foster Nov. 4, 1952 2,629,325 Sweetman Feb. 24, 1953 2,669,928 Sweetman Feb. 23, 1954 2,733,657 Bryant et al. Feb. 7, 1956 

